Abstract: An amplifying unit performs a differential amplification with a highest level or a lowest level of an input signal and a previous input signal. A semiconductor element transfers a signal level output from the amplifying unit from a second terminal to a third terminal by using a current conducted from the second terminal to the third terminal in response to a voltage applied to a first terminal. A control unit controls the voltage applied to the first terminal of the semiconductor element based on a voltage or a current related to a reference semiconductor element. A holding unit holds a signal level output from the third terminal of the semiconductor element.

Abstract: An optical reception circuit and an identification level controlling method for an optical reception circuit are disclosed wherein reception sensitivity degradation arising from transmission waveform degradation by chromatic dispersion can be suppressed. The optical reception circuit includes a photoelectric converter for converting reception light into an electric signal, a pre-amplifying unit for amplifying the electric signal, a main amplifier for amplifying an output of the pre-amplifying unit, a monitor for monitoring the output of the pre-amplifying unit, and a controller for controlling an identification level in the main amplifier based on an output of the monitor. The monitor includes a limiter amplifier for amplifying the output of the pre-amplifying unit, and an average value detector for detecting a time average value of an output amplitude of the limiter amplifier.

Abstract: In an optical switch controller, in order that residual vibration at movement control of a movable body such as a tilt mirror can be reduced and controlled with high accuracy, a processing unit outputs a driving signal for controlling the angle of the tilt mirror, the driving signal is D/A converted by a D/A converter and then is changed to a high-voltage signal by a high-voltage amplifier to be supplied to the tilt mirror, the electrostatic capacity of the tilt mirror changes corresponding to angle change of the tilt mirror, a mirror-angle detecting unit detects the electrostatic capacity and feeds back it as a correction value to a processing unit, and the processing unit corrects the driving signal using a correction value obtained when the angle of the tilt mirror is actually changed.

Abstract: In an optical telecommunication system in which an intensity of an arriving optical signal is different for each packet, detected is an optical intensity for each packet with little error. For this purpose, contrived is to detect an average optical intensity across header parts for each packet by focusing on the fact that the header part comprising the preamble and delimiter of a packet is in a bit pattern which includes approximately the same numbers of “0” and “1”.

Abstract: The present invention is directed to an optical module, which stabilizes an oscillation characteristic of a laser by means of a simple configuration. To this end, a gain member, a partial reflection section connected to the gain member, and an optical device section connected to the partial reflection section are formed integrally into an apparatus of the present invention. The partial reflection section includes an optically-coupling waveguide section having a first light waveguide connected to the gain member, and a second light waveguide which has an optical axis differing from that of the first light waveguide and which is optically coupled to the first light waveguide and optically connected to the optical device section; and a first total reflection mirror formed at an end of the first light waveguide facing the optical device section.

Abstract: An optical receiver includes: a converting unit that converts an optical signal into an electrical signal; an amplifying unit that amplifies the electrical signal; a regenerating unit that regenerates the amplified electrical signal; a correcting unit that performs correction of an error included in the regenerated electrical signal; a monitoring unit that performs monitoring of an optical current flowing through the converting unit; and a control unit that calculates a decision threshold based on a result of the correction and a result of the monitoring.

Abstract: A light receiving device is disclosed by which a reception characteristic of a light receiving system can be improved. The light receiving device includes a photoelectric conversion element for receiving a light signal and performing photoelectric conversion of the light signal, and a data detection section for using an decision level for the light signal received by the photoelectric conversion element to detect modulation data included in the light signal. The light received device further includes an decision level control section for feedforward controlling the decision level to be used by the data detection section based on a level of the received light signal.

Abstract: An optical wavelength switch having a planar wave guide formed on a substrate is disclosed that comprises a wave-guide-type diffraction grating which includes an input/output wave guide having an under-clad layer on a sacrificial layer formed on the substrate, a core layer formed on the under-clad layer and an over-clad layer formed on the core layer, a first slab wave guide connected with the input/output wave guide, an array wave guide whose one side is connected with the first slab wave guide, and a second slab wave guide with which the other side of the array wave guide is connected; and a movable girder whose one end is firmly secured to the substrate, the movable girder having the same under-clad layer, core layer and over-clad layer as those of the wave-guide-type diffraction grating, wherein the optical wavelength switch has a reflecting mirror at the tip of the movable girder, the reflecting mirror facing an end face of the second slab wave guide, with the position of the reflecting mirror being set

Abstract: An optical waveguide used in a WDM optical transmission system are fabricated by the following steps in order to be highly integrated and reduced in size and to have a more preferable design. Namely, a first cladding and a first core are formed on a substrate; at least the first core is etched so as to remain a first waveguiding part for guiding light and non-waveguiding parts, disposed on the both sides of the waveguiding part along a guiding direction of the guiding of light, for guiding no light and in such a manner that two grooves, having varying widths in the guiding direction respectively, are formed between the waveguiding part and each of the non-waveguiding parts; a second cladding is deposited on the remaining first core and the fist cladding; and the second cladding is reflowed by a heat treatment so as to be flattened.

Abstract: A radio communication device of an example of the present invention is one capable of communicating a plurality kinds of radio communicating media having different resonant frequencies comprises a transmission unit having a first resonant frequency tuned to and resonated with the resonant frequencies of the radio communication media in a prescribed communication range with the radio communication media to transmit signals to the radio communication media and a reception unit having a second resonant frequency not resonated with the resonant frequencies of the radio communication media in the prescribed communication ranges with the radio communication media to receive signals from the radio communication media.

Abstract: An optical wavelength switch having a planar wave guide formed on a substrate is disclosed that comprises a wave-guide-type diffraction grating which includes an input/output wave guide having an under-clad layer on a sacrificial layer formed on the substrate, a core layer formed on the under-clad layer and an over-clad layer formed on the core layer, a first slab wave guide connected with the input/output wave guide, an array wave guide whose one side is connected with the first slab wave guide, and a second slab wave guide with which the other side of the array wave guide is connected; and a movable girder whose one end is firmly secured to the substrate, the movable girder having the same under-clad layer, core layer and over-clad layer as those of the wave-guide-type diffraction grating, wherein the optical wavelength switch has a reflecting mirror at the tip of the movable girder, the reflecting mirror facing an end face of the second slab waveguide, with the position of the reflecting mirror being set d

Abstract: An optical waveguide device serving as a planar lightwave circuit, and an optical waveguide device which enables an attempt to realize greater functionality as a planar optical waveguide device. An optical waveguide device is configured to have a first cladding layer, a core formed on the first cladding layer for guiding light, and a second cladding layer formed on the first cladding layer and the core so as to surround the core, wherein the core comprises a trunk portion constituting a body of the core and a layered structure portion essentially perpendicular to a plane forming the first cladding layer.

Abstract: A light receiving device is disclosed by which a reception characteristic of a light receiving system can be improved. The light receiving device includes a photoelectric conversion element for receiving a light signal and performing photoelectric conversion of the light signal, and a data detection section for using an decision level for the light signal received by the photoelectric conversion element to detect modulation data included in the light signal. The light received device further includes an decision level control section for feedforward controlling the decision level to be used by the data detection section based on a level of the received light signal.

Abstract: An optical waveguide, a fabrication method therefor and an optical waveguide device are disclosed wherein a sink of a core layer (waveguide core) can be suppressed while formation of cracks and air bubbles is suppressed. The optical waveguide comprises a substrate, and a lower clad layer, a core layer and an upper clad layer formed on the substrate such that the core layer is buried within the upper and lower clad layers. The lower clad layer is formed from a silica glass-type material, which is formed using a trialkylsilyl-type compound as an organic source, such that the melting temperature thereof is higher by a predetermined temperature or more than that of the upper clad layer.

Abstract: An optical waveguide device serving as a planar lightwave circuit, and an optical waveguide device which enables an attempt to realize greater functionality as a planar optical waveguide device. An optical waveguide device is configured to have a first cladding layer, a core formed on the first cladding layer for guiding light, and a second cladding layer formed on the first cladding layer and the core so as to surround the core, wherein the core comprises a trunk portion constituting a body of the core and a layered structure portion essentially perpendicular to a plane forming the first cladding layer.

Abstract: A burst signal detection circuit for detecting the arrival of a burst-like signal, which can accurately detect the burst signal against the DC level variations even in the case where the arriving burst signal is a weak signal, is disclosed. A DC variation removing circuit detects the bottom level of an input signal and removes the DC level variation of the input signal based on the bottom level. An amplitude identifying circuit detects the presence or absence of a burst signal based on the output signal of the DC variation removing circuit. The amplitude identifying circuit includes an amplitude detection circuit for detecting the maximum amplitude of the output signal of the DC variation removing circuit, a threshold level control circuit for controlling the threshold level and a comparator for comparing the output level of the amplitude detection circuit with the threshold level and outputting a detection signal indicating the presence or absence of a burst signal.

Abstract: In an optical switch controller, in order that residual vibration at movement control of a movable body such as a tilt mirror can be reduced and controlled with high accuracy, a processing unit outputs a driving signal for controlling the angle of the tilt mirror, the driving signal is D/A converted by a D/A converter and then is changed to a high-voltage signal by a high-voltage amplifier to be supplied to the tilt mirror, the electrostatic capacity of the tilt mirror changes corresponding to angle change of the tilt mirror, a mirror-angle detecting unit detects the electrostatic capacity and feeds back it as a correction value to a processing unit, and the processing unit corrects the driving signal using a correction value obtained when the angle of the tilt mirror is actually changed.

Abstract: An optical wavelength switch having a planar wave guide formed on a substrate is disclosed that comprises a wave-guide-type diffraction grating which includes an input/output wave guide having an under-clad layer on a sacrificial layer formed on the substrate, a core layer formed on the under-clad layer and an over-clad layer formed on the core layer, a first slab wave guide connected with the input/output wave guide, an array wave guide whose one side is connected with the first slab wave guide, and a second slab wave guide with which the other side of the array wave guide is connected; and a movable girder whose one end is firmly secured to the substrate, the movable girder having the same under-clad layer, core layer and over-clad layer as those of the wave-guide-type diffraction grating, wherein the optical wavelength switch has a reflecting mirror at the tip of the movable girder, the reflecting mirror facing an end face of the second slab waveguide, with the position of the reflecting mirror being set d

Abstract: An optical waveguide, a fabrication method therefor and an optical waveguide device are disclosed wherein a sink of a core layer (waveguide core) can be suppressed while formation of cracks and air bubbles is suppressed. The optical waveguide comprises a substrate, and a lower clad layer, a core layer and an upper clad layer formed on the substrate such that the core layer is buried within the upper and lower clad layers. The lower clad layer is formed from a silica glass-type material, which is formed using a trialkylsilyl-type compound as an organic source, such that the melting temperature thereof is higher by a predetermined temperature or more than that of the upper clad layer.

Abstract: An optical multiplexer/demultiplexer that the passband characteristic of demultiplexed optical signal in a waveguide on the output side can be controlled accurately. Long and narrow guide waveguides, being areas where an effective refractive index is greater than an effective refractive index of a sector slab waveguide on the input side, are formed in the core or in an area adjacent to the core so that the long and narrow guide waveguides will branch at the center of curvature of the sector slab waveguide and so that the long and narrow guide waveguides will extend in an output direction without intersecting with one another. When optical signal is input to the sector slab waveguide, the light is guided more strongly through areas where the guide waveguides are formed. As a result, with the propagation of the optical signal, a peak corresponding to the shape of the guide waveguides will appear in the shape of a mode of the optical signal.